MOLECULAR-DYNAMICS SIMULATIONS OF FLUOROSILYL SPECIES IMPACTING FLUORINATED SILICON SURFACES WITH ENERGIES FROM 0.1 TO 100 EV

A better understanding of the surface interactions of energetic atomic and molecular species is needed under conditions relevant to plasma-a ssisted etching and deposition. In this article we describe the result s of molecular dynamics (MDs) simulations of atomic Si and molecular S iFx (x=1-3) species impacting fluorinated silicon surfaces. These impa cting species might be sputtered species incident on feature surfaces with energies typically on the order of a few eV, or etch products tha t are ionized in the plasma and accelerated back towards the substrate surface to attain energies on the order of tens to hundreds of eV. To model both of these cases, the incident energy was varied from 0.1 to 100 eV. We performed the MD simulations to investigate the types of p ossible events that occur during the picosecond(s) following the impac t of these reactive atomic and molecular species. Stillinger-Weber pot entials were used to model the interatomic interactions [Phys. Rev. B 31, 5262 (1985); J. Chem. Phys. 88, 5123 (1988); Phys. Rev. Lett. 62, 2144 (1989); J. Chem. Phys. 92, 6239 (1990)]. We observed a variety of events in the simulated trajectories: sticking or reflection of the i mpacting species, reactions with surface species, sputtering of surfac e material, and dissociation of the impacting molecular species. The e ffect of surface coverage and incident angle was studied by simulating impacts onto three silicon surfaces with different amounts [monolayer s (MLs)] of fluorine (0 ML F, 1 ML F, 2 ML F), and by varying the inci dent angle of Si atoms from 0 degrees to 75 degrees from the surface n ormal. These effects are illustrated for select cases. (C) 1997 Americ an Vacuum Society.